The invention concerns a method and a device for producing filled containers from preforms made of a thermoplastic material.
The manufacture of containers by blow-molding from preforms made of a thermoplastic material, for example from preforms made of PET (polyethyleneterephthalate), is known, wherein the preforms are supplied to different machining stations inside a blow-molding machine (DE-OS 43 40 291). Typically, a blow-molding machine has a heating device for the tempering or pre-heating (thermal conditioning) of the preforms and a blow-molding installation with at least one blow-molding station, in the area of which the in each case previously tempered preform is expanded biaxially or multiaxially into a container. The expansion occurs with the help of a compressed gas (compressed air) as the pressure medium which is introduced in the preform to be expanded by means of a molding pressure. The process-engineering procedure for a preform expansion such as this is explained in DE-OS 43 40 291.
The basic structure of the blow-molding station is described in DE-OS 42 12 583. Options for tempering the preforms are explained in DE-OS 23 52 926.
According to a typical further processing method, the containers made by blow-molding are supplied to a subsequent filling installation and here are filled with the planned product or filling material. Thus, a separate blow-molding machine and a separate filling machine are used. Also known, furthermore, is combining the separate blow-molding machine and the separate filling machine to form one machine block, i.e. to form a blocked blow-molding and filling installation, wherein moreover the blow-molding and the filling take place on separate machine components and chronologically consecutively.
It has furthermore already been proposed to produce containers, in particular also in the form of bottles made of thermally conditioned or pre-heated preforms and moreover at the same time to fill them with a liquid filling material, which is supplied as a hydraulic pressure medium to expand the preform and to mold the container with a molding and filling pressure, so that the particular preform is shaped into the container at the same time as the filling. Certain problems with methods of this kind are that the contamination of the particular molding and filling station or the mold forming this station, which is made similar to a blow-mold of a blow-molding machine for producing containers made of thermally conditioned preforms by blowing with a compressed gas, need to be avoided. Especially in the case of a full or partial carbonation of the filling material, there is to a particular degree the danger of a contamination of the particular molding and filling station by filling material losses, in particular at the lowering of the internal pressure of the container, i.e. when depressurising the container from the very high molding and filling pressure to the ambient pressure. Filling material losses of this kind are caused in particular by a massive formation of foam at depressurisation, so that the simultaneous molding and filling of containers could hitherto not be used where preforms were used and where the filling material was used as a pressure medium (hydraulic molding technology), in particular for products containing CO2.
Moreover, at the end of the particular molding and filling process, filling material necessarily remains on and in the molding and filling elements. This filling material drips off at least partially and/or, due to air movement, spreads inside the molds of the molding and filling stations and thereby contaminates in particular also critical surfaces, i.e. surfaces which, during molding and filling, come into contact with the filling material and/or with areas of the containers close to the filling material and/or touching the filling material, so that due to microbial growth on the surfaces contaminated with the filling material, a microbiological risk to the filling material and also to people, in particular service personnel, arises.